A semiconductor memory as a semiconductor device is mounted on various electronic equipment. Recently, resistance change memories such as ReRAM (Resistive RAM) using a variable resistance device as a memory device, PCRAM (Phase Change RAM) using a phase change device as a memory device, and the like have received attention as a next generation non-volatile semiconductor memory.
These resistance change memories have a feature in that a memory cell array is of a cross point type and can realize a large memory capacity by a three-dimensional integration and operation at a high speed similar to a DRAM (refer to, for example, Jpn. PCT National Publication No. 2005-522045).
In the resistance change memory, a cross point type memory cell array includes cell units. Each of the cell units is formed of a memory device and a non-ohmic device. In the cross point type memory cell array, the cell units are disposed two-dimensionally as well as stacked in a vertical direction with respect to a substrate surface.
The resistance change memory having the stacked structure includes a contact electrode for connecting an interconnect having a certain interconnect level and another interconnect having a different interconnect level (an upper layer or a lower layer) (refer to, for example, Jpn. Pat. Appln. KOKAI Publication No. 2009-130140 reference). In the cross point type memory cell array, a contact portion connected to the contact electrode is disposed to a part of the interconnect.
In a semiconductor device such as the resistance change memory, when a connecting state of a contact electrode and an interconnect (contact portion) is deteriorated, a contact resistance of the contact electrode and the interconnect is increased, and electric characteristics of each interconnect are dispersed. Further, when an area for disposing the contact electrode and the contact portion is simply reduced here, the dispersion of the electric characteristics is increased.